Importance of antibOdies in diagnosis 397 



into groups and types. This work has assumed great importance 

 because of the consistency with which group "A" streptococci are 

 associated with human infection. 



Skin Tests for Antibodies. — Other tests for the presence of 

 antibodies or antibody-like substances are in common use: The 



Fig. 18.— Type II pneumococcus in sputum mixed with Type I antiserum (rab- 

 bit) ; no "quellung-." (After Sabin. J. A. M. A. 1933.) 



Fig-. 19. — Type II pneumococcus in sputum mixed with Type II antiserum (rab- 

 bit) ; "quellung" reaction. (After Sabin, J. A. M. A. 1933.) 



Schick test and Dick test for the presence of diphtheria and scarlet 

 fever antitoxin respectively and the various tests for allergic 

 reagins. 



The Francis Skin Test, — This test, according to Edwards, 

 Hoagland and Thompson (1939), consists of the injection of 0.05 

 c.c. of a dilution of 1 : 1,000 type specific pneumococcus polysac- 

 charide in physiological saline intracutaneously on the flexor sur- 

 face of the forearm, A positive result consists of an urticaria-like 



